Parshas Shelach:He'oros on Challah

1) The Noda B'Yehuda (YD Tanyina Siman 201) discusses the issue of how is it that you are mikayeim the mitzvah of hafrasha with a chita achas yet the nesina (amount given to the kohein) needs to be a shiur chashuv ( by challah 1/24). He writes that he has a chiddush that is not found anywhere, namely that the mitzvah of terumah,challah etc is one mitzvah with 2 inyanim a) to be mafkia the tevel b) the nesina which is the ikar mitzvah. Therefore, to be mafkia the tevel you only need a hafrasha of chita achas but the nesina needs a shiur.

The hagahos from his son points out that the Noda B'Yehuda doesn't mean that I can be mafrish a chita and give more than that as the nesina. Rather, only what I am mafrish I need to give. It comes out that l'chatchilah in order to be m'kayeim the nesina of a davar chashuv I need to be mafrish a perutah also.

The Noda B'Yehuda uses this yesod to explain the Rashi's in this weeks parsha.Ayin sham kol hadevorim.

2) The Minchas Asher points out that the Shoeil U'Meishiv in his hagahos to the Noda B'Yehuda writes that this chiddush of the Noda B'Yehuda is actually a Tosfos Rid in Kiddushin (Daf 58)

3) The Marginisa Tuva writes in interesting chiddush in Sefer HaMitzvos Shoresh 12. He says that the hafrashas teruma is really being given to Hashem. When the kohein gets his cheilek he is not getting it from teh Yisroel but rather he is getting it "m'shulchan gavoha". That is why there is no mitzvas nisana on the Yisroel, since the Yisroel doesn't gibe teh kohein anything.

4) There is a diyun in the Achronim whether hafrasha counts if you have no intention to give it. The Har Tzvi (Zeraim Siman 44) has a whole arichus on it. It is nogeia b'zman hazeh where we destroy the teruma we separate. The Har Tzvi understands that this is called doing a hafrasha w/out intent to give it to anyone.